The present invention relates to battery charging and, in particular, to the charging of batteries used in portable devices such as cellular telephones.
Advances in integrated circuit and battery technology have enabled the ongoing reduction in the size of many electronic devices, such as cellular telephones. Among the advantages of this size reduction are reduced manufacturing costs, reduced power consumption and enhanced convenience for the user. For example, the original cellular phones were not unlike traditional military CB radios and, as such, were large and heavy. By contrast, some cellular phones now on the market are so small as to be able to be carried comfortably in one's pocket or purse.
Portable re-chargeable electronic devices such as cellular telephones must be connected to a power supply to re-charge their batteries. These devices typically employ some form of warning signal such as a beeping tone, warning light or vibration that indicates when the battery requires re-charging. Some devices even have a more sophisticated system which indicates battery charge level continuously. These systems are deployed as integral parts of the portable device or as part of the battery pack of the portable device.